CX500 GL500 650 Global

So just today I noticed an very small drop of coolant on the flat block of the engine, near the water pump but not directly underneath it. It was maybe a drop or 2, directly under my carbs idle adjust knob. There was no trail of coolant, the rest of the engine block looked dry, but the liquid was definitely green coolant so it must have come from somewhere. My oil looks good, so I don't think it's mixing with any coolant. I check the oil and coolant regularly, and I haven't noticed a drop in the coolant level, so this must be a very small leak where ever it is from. If it is my mech seal, would there be an unmistakable trail of coolant, or could it possible evaporate before I noticed it? I'll try to take a picture of it tomorrow, I just noticed it today when I got home from work.

Wipe the area clean and run again.Could be just a little from an o-ring from the coolant pipe or from the pipe from the thermostat to the back of the engine.If not it's no biggy just let us know

So I've been keeping an eye on things, and the coolant leak is getting a little bit worse. It's not gushing out, but there is a definite trickle of coolant after a longish ride. The coolant level still hasn't dropped much, but I think it is down a little. The oil looks clean, so I don't think the coolant is mixing into the oil. It seems to be originating from behind the coolant pipe, not the pipe itself. Does this sound like the mech seal leaking? I've read Shep's "in bike" replacement; does this sound like the rubber piece failing? Should I be worried about this, and should I stop riding until it's fixed, or is this something that, as long as it doesn't get worse, I can keep riding? It stops leaking when I turn the bike off, if that helps diagnose the problem. Let me know if there are any other pieces of info y'all need to help me diagnose, thanks ahead of time.

It does sound like the Mech seal is going.You can keep running but also check the coolant level using the Rad cap off.The overflow bottle does not give a correct reading and should not be used as a measure of the coolant level in the Radiator.

You can use the cheaper inner of the Yamaha Mech seal and I would do so ASAP.It's not a hard job using my method.I can di it in less than 45 mins.1st time allow a couple of hours so you can clean and inspect the bits.

Yamaha 11H-12438-10-00

Mine has been weeping from the mech since I bought it, roughly 1100 miles ago. I've been keeping an eye on the radiator level and not the jug like as Shep suggested. No problems so far, planning on doing Shep's Yammy seal swap this winter.

If I can find a yamaha seal tomorrow I'll probably try fixing it this weekend. Other than the seal, are there any other parts/pieces I should buy ahead of time? Do I need a new gasket for the water pump? Anything else, other than following the directions, that I should know or look out for?

Just hope the Water pump seal is ok and the copper crush washer is serviceable.I re-anneal mine on my gas stove till they are,"Cherry Red" and then let nature cool them down,not quench.If the seal is dubious I use a bit of RTV and wipe clean but not bothered if a small bit gets into the cooling system,it can take it.

After searching for the yamaha and the honda seals and with nobody at all having either, I asked a yamaha dealer to order one for me, and it finally came in and just looking at it, without even comparing it to the original its WAY too big, its not even close to the correct part number so I don't know what the parts dept. did but it's definitely not a mech seal for my bike. It's almost an inch and a half in diameter and close to 2 inches long, I wish I'd opened the box before I got home so I could have avoided the return trip. Now I have to find another. Any of you know of a good source for mail order for this yamaha seal? In the mean time, as long as the oil looks good and I check my coolant level every few days I should be ok, right? I only have a few weeks of riding time left and don't want to put it away before I have to, but I don't want to break anything either.

I'm sorry they have screwed up on you.You will have no problems running the bike just as you say keep an eye on it